Adding microscopic porosity to the surface of a microcoil to be used for medical implantation

ABSTRACT

A vasoocclusive microcoil for therapeutic treatment of a patient&#39;s vasculature includes a surface with a plurality of voids or pores therein, and a therapeutic or bioactive material disposed within the plurality of voids or pores. The therapeutic or bioactive material within the plurality of voids or pores operates to accelerate a healing process in the patient&#39;s vasculature when the microcoil is introduced into the patient&#39;s vasculature.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is based upon Provisional patent application Ser. No.60/647,516, filed Jan. 26, 2005.

BACKGROUND OF THE INVENTION

Microcoils have been developed for implantability into aneurysms as ameans of promoting healing through the obstruction of pulsatile bloodflow into the center of the promoting aneurysm. Such devices have becomevery successful in treatment of cranial aneurysms and as a method oftreating and preventing stroke when such malformations are discovered.

Another embolic coil is known which includes a distal roughened,textured surface with pockets having diameters of about 0.125 to 50microns and depths of about 0.25 to 20 microns to provide improvedplatelet adhesion and to promote clotting. Another type of removableocclusion system for treating the neck of an aneurysm includes a meshportion with pores allowing blood to flow through the mesh portion.While such embolic devices have voids or pores that can promote clottingor allow blood flow through the device, it would be desirable to providean embolic device that can further promote healing of a patient'svasculature.

One vasoocclusive coil is known that has an enhanced therapeutic strandstructure that may be formed from or incorporate therapeutic orbioactive materials such as polyglycolic acid (PGA) or poly(D,L-lacticacid-co-glycolic acid) (PGLA), or other therapeutic materials. Anotherembolic device is known which includes embolizing elements made of ahydrophilic, macroporous, polymeric, hydrogel foam material.

While the microcoil treatment of aneurysms is highly effective inimproving the prognosis for recovery of those with such malformations,it is believed that success rate of the procedures would be enhanced ifnew and effective methods of treatment of the micro coils could be usedto enhance the healing process once the microcoils are placed. Thepresent invention resolves these and other limitations in prior artdevices.

The present invention treats microcoils and other implantable devices,using one or more of a variety of etching methods, which can includeplasma etching, photolithography and chemical etching, to createmicroscopic voids in the surface of a microcoil which are complex inshape and adapted to receive into the surface by pressure, melting ordeposition one or more of a variety of therapeutic agents, therapeuticmaterials and therapeutic plastic agents which can act to accelerate thehealing process once the coil is in place. At the present time, agentswhich are believed to be appropriate for deposition in the voids createdby the process include therapeutic drugs and agents such as PGA or PGLA,among others, which can act as an accelerant for the healing process.

The present invention accordingly provides for a vasoocclusive microcoilfor therapeutic treatment of a patient's vasculature, including avasoocclusive microcoil having at least a portion having a surfacedefining a plurality of voids or pores therein, and a therapeutic orbioactive material disposed within the plurality of voids or pores. Thepresent invention also provides for a method for occluding a patient'svasculature, involving the steps of providing a vasoocclusive microcoilhaving at least a portion having a surface defining a plurality of voidstherein, and a therapeutic/bioactive material disposed within theplurality of voids, and introducing the vasoocclusive microcoil into thepatient's vasculature, whereby the therapeutic/bioactive material canact to accelerate a healing process in the patient's vasculature. Thepresent invention also provides for a method for delivering atherapeutic agent or material to a patient's vasculature by such amicrocoil having at least a portion with a surface having a plurality ofvoids or pores, and for controlling the delivery of the therapeuticagent or material by controlling the porosity of the surface of themicrocoil. The present invention also provides for a method ofdelivering a hydrogel to a patient's vasculature by a microcoil havingat least a portion with a surface having a plurality of voids or porescarrying the hydrogel. The present invention also provides for a methodfor forming porosity in a surface of a microcoil using one or more of avariety of etching methods, which can include plasma etching andsputtering.

The therapeutic agent or material may be a therapeutic drug or atherapeutic plastic agent which can act to accelerate the healingprocess once the coil is in place, and in a presently preferred aspect,the therapeutic agent or material may be polyglycolic acid orpoly(D,L-lactic acid-co-glycolic acid), and/or a therapeutic drug. Morebroadly, the therapeutic material may be silk, collagen, elastin,polyglycolic acid, polylactic acid, poly(D,L-lactic acid-co-glycolicacid), poly(L-lactide), poly(L-lactide-co-D,L-lactide),poly(L-lactide-co-glycolide), poly(glycolide-co-trimethylene carbonate),polyethylene oxide, polydioxanone, polycaprolactone, hylauric acid,polyhydroxylbutyrate, poly(phosphazene),poly(D,L-lactide-co-caprolactone), poly(glycolide-co-caprolactone),polyvinyl alcohol, polyanhydrides thereof, poly(ortho esters) thereof,poly(phosphate esters) thereof, poly(amino acids) thereof, poly(hydroxybutyrates) thereof, copolymers thereof, composites thereof, orcombinations thereof. The therapeutic material may also beethylene-octene copolymer, polypropylene, polyethylene, polyacrylate,polyacrylamide, poly(hydroxyethyl methacrylate), polyurethane,polysiloxane, copolymers thereof, composites thereof, or combinationsthereof.

Other features and advantages of the present invention will become moreapparent from the following detailed description of the preferredembodiments in conjunction with the accompanying drawings, whichillustrate, by way of example, the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective of a portion of a microcoil according to theinvention.

FIG. 2 is a cross-section at 2-2 of FIG. 1.

FIG. 3 shows a portion of a helical multi-stranded microcoil formedaccording to the invention.

FIG. 4 shows a portion of a helical single-stranded microcoil formedaccording to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As is illustrated in the drawings, which are provided for the purposesof illustration and not by way of limitation, the invention is embodiedin a vasoocclusive microcoil having at least a portion with a surfacedefining a plurality of voids or pores therein, with a therapeutic orbioactive material within the voids or pores. In a presently preferredaspect illustrated in FIG. 1, the vasoocclusive microcoil may be formedfrom one or more flexible strands 12 of a resilient material and/orsuper-elastic material, such as nickel titanium alloy, for example. Thenickel titanium alloy is typically heat treated such that the alloy ishighly flexible at a temperature appropriate for introduction into thebody via a catheter. By choosing such a material for micro-coils and thelike, the devices formed from the micro-cable can be relatively easilyplaced into the appropriate body cavity and after placement, the devicewill take on a shape designed to optimize the therapeutic purposesdesired for the device.

As illustrated in FIG. 2, the vasoocclusive microcoil may also include acentrally, axially disposed radiopaque wire 14, which can be formed ofplatinum or gold, for example, or other similar suitable radiopaquemetals, in order to provide a radiopaque marker of the deployedconfiguration of a device made of the vasoocclusive microcoil duringvascular surgery.

One advantageous application of the invention is to vasooclusive devicesformed of the vasoocclusive microcoil for insertion into aneurysms andother vascular defects for the purpose of occluding flow to theaneurysm. FIG. 3 illustrates a portion of a helically wound coil 16 ofthe vasoocclusive microcoil 10, which is formed to fit within amicro-catheter for insertion into an area upon which a therapeuticprocedure is to be performed. FIG. 4 illustrates a portion of ahelically wound coil 16′ of the vasoocclusive microcoil 10′, which isformed to fit within a micro-catheter for insertion into an area uponwhich a therapeutic procedure is to be performed. While helical coilsare illustrated, it will be appreciated that numerous other shapes canbe formed from the vasoocclusive microcoil of the invention.

As is illustrated in FIGS. 1 and 4, the vasoocclusive microcoil includesat least a portion having a surface defining a plurality of microscopicvoids or pores 18 in the surface of the microcoil, which may be complexin shape. The voids or pores may be formed in the surface of themicrocoil using one or more of a variety of sputtering and etchingmethods, which can include plasma etching, photolithography and chemicaletching, for example, and any combination or combinations thereof. Othermethods of creating microscopic voids or pores in the surface of animplantable device can be effective when combined with the ability todeposit, press, or melt a healing accelerant therapeutic and/orbioactive material into the surface.

The voids or pores are advantageously formed to receive and retain avariety of therapeutic and/or bioactive agents which can act toaccelerate the healing process once the coil is in place. The agents maybe deposited in the voids or pores by pressure, melting or deposition,or the like. At the present time, agents which are believed to beappropriate for deposition in the voids or pores created by the processinclude polyglycolic acid (PGA) and poly(D,L-lactic acid-co-glycolicacid) (PGLA), which can act as an accelerant for the healing process.Other therapeutic and/or bioactive agents that may be deposited in thevoids or pores include polylactic acid or poly(D,L-lactide) (PLA),poly(D,L-lactide-co-glycolide) (PLA/PGA), poly(L-lactide) (PLLA),poly(L-lactide-co-D,L-lactide) (PLLA/PLA), poly(L-lactide-co-glycolide)(PLLA/PGA), poly(glycolide-co-trimethylene carbonate) (PGA/PTMC),polyethylene oxide (PEO), polydioxanone (PDS), polycaprolactone (PCL),hylauric acid, polyhydroxylbutyrate (PHBT), poly(phosphazene),poly(D,L-lactide-co-caprolactone) (PLA/PCL),poly(glycolide-co-caprolactone) (PGA/PCL), polyvinyl alcohol (PVA),polyanhydrides (PAN), poly(ortho esters), poly(phosphate ester),poly(amino acid), poly(hydroxy butyrate), copolymers of these materialsas well as composites and combinations thereof; non-metallic fibermaterial, such as silk, collagen, elastin or other connecting proteins;plastic or other polymers such as an ethylene-octene copolymer,polypropylene, polyethylene, polyacrylate, polyacrylamide,poly(hydroxyethyl methacrylate), polyurethane, polysiloxane and theircopolymers. The therapeutic and/or bioactive non-metallic fiber materialmay be bioabsorbable or non-absorbable. The therapeutic and/or bioactivenon-metallic fiber material may also be used for absorbing and releasingone or more therapeutic agents.

It will be apparent from the foregoing that while particular forms ofthe invention have been illustrated and described, various modificationscan be made without departing from the spirit and scope of theinvention. Accordingly, it is not intended that the invention belimited, except as by the appended claims.

1. A vasoocclusive microcoil for therapeutic treatment of a patient'svasculature, comprising: a vasoocclusive microcoil including at least aportion having a surface defining a plurality of voids therein; and atherapeutic/bioactive material disposed within said plurality of voids.2. The vasoocclusive microcoil of claim 1, wherein said therapeuticmaterial is a plastic agent which can act to accelerate the healingprocess once the coil is in place.
 3. The vasoocclusive microcoil ofclaim 1, wherein said therapeutic material is selected from the groupconsisting of polyglycolic acid and poly(D,L-lactic acid-co-glycolicacid).
 4. The vasoocclusive microcoil of claim 1, wherein saidtherapeutic material is selected from the group consisting of silk,collagen, elastin, polyglycolic acid, polylactic acid, poly(D,L-lacticacid-co-glycolic acid), poly(L-lactide), poly(L-lactide-co-D,L-lactide),poly(L-lactide-co-glycolide), poly(glycolide-co-trimethylene carbonate),polyethylene oxide, polydioxanone, polycaprolactone, hylauric acid,polyhydroxylbutyrate, poly(phosphazene),poly(D,L-lactide-co-caprolactone), poly(glycolide-co-caprolactone),polyvinyl alcohol, polyanhydrides thereof, poly(ortho esters) thereof,poly(phosphate esters) thereof, poly(amino acids) thereof, poly(hydroxybutyrates) thereof, copolymers thereof, composites thereof, andcombinations thereof.
 5. The vasoocclusive microcoil of claim 1, whereinsaid therapeutic material is selected from the group consisting ofethylene-octene copolymer, polypropylene, polyethylene, polyacrylate,polyacrylamide, poly(hydroxyethyl methacrylate), polyurethane,polysiloxane, copolymers thereof, composites thereof, and combinationsthereof.
 6. The vasoocclusive microcoil of claim 1, wherein saidtherapeutic material is a therapeutic drug.
 7. A method for occluding apatient's vasculature, comprising: providing a vasoocclusive microcoilincluding at least a portion having a surface defining a plurality ofvoids therein, and a therapeutic/bioactive material disposed within saidplurality of voids; and introducing said vasoocclusive microcoil intothe patient's vasculature, whereby said therapeutic/bioactive materialcan act to accelerate a healing process in the patient's vasculature. 8.The method of claim 7, wherein said therapeutic material is a plasticagent which can act to accelerate the healing process once the coil isin place.
 9. The method of claim 7, wherein said therapeutic material isselected from the group consisting of polyglycolic acid andpoly(D,L-lactic acid-co-glycolic acid).
 10. The method of claim 7,wherein said therapeutic material is selected from the group consistingof silk, collagen, elastin, polyglycolic acid, polylactic acid,poly(D,L-lactic acid-co-glycolic acid), poly(L-lactide),poly(L-lactide-co-D,L-lactide), poly(L-lactide-co-glycolide),poly(glycolide-co-trimethylene carbonate), polyethylene oxide,polydioxanone, polycaprolactone, hylauric acid, polyhydroxylbutyrate,poly(phosphazene), poly(D,L-lactide-co-caprolactone),poly(glycolide-co-caprolactone), polyvinyl alcohol, polyanhydridesthereof, poly(ortho esters) thereof, poly(phosphate esters) thereof,poly(amino acids) thereof, poly(hydroxy butyrates) thereof, copolymersthereof, composites thereof, and combinations thereof.
 11. The method ofclaim 7, wherein said therapeutic material is selected from the groupconsisting of ethylene-octene copolymer, polypropylene, polyethylene,polyacrylate, polyacrylamide, poly(hydroxyethyl methacrylate),polyurethane, polysiloxane, copolymers thereof, composites thereof, andcombinations thereof.
 12. A method for delivering a therapeutic drug toa patient's vasculature, comprising: providing a vasoocclusive microcoilincluding at least a portion having a surface defining a plurality ofvoids therein, and a therapeutic drug disposed within said plurality ofvoids; and introducing said vasoocclusive microcoil into the patient'svasculature.
 13. The method of claim 12, further comprising the step ofcontrolling delivery of the therapeutic drug by controlling porosity ofsaid surface defining a plurality of voids therein.
 14. A method fordelivering a hydrogel to a patient's vasculature, comprising: providinga vasoocclusive microcoil including at least a portion having a surfacedefining a plurality of voids therein, and a hydrogel disposed withinsaid plurality of voids; and introducing said vasoocclusive microcoilinto the patient's vasculature.
 15. A method for forming a vasoocclusivemicrocoil including at least a portion having a surface defining aplurality of voids therein, comprising: providing a vasoocclusivemicrocoil; forming a plurality of voids on the surface of thevasoocclusive microcoil by a process selected from the group consistingof sputtering and etching, and a combination thereof.
 16. The method ofclaim 15, wherein etching comprises an etching process selected from thegroup consisting of plasma etching, photolithography and chemicaletching, and combinations thereof.